From: "Darrick J. Wong" djwong@kernel.org
[ Upstream commit 41667260bc84db4dfe566e3f6ab6da5293d60d8d ]
XFS does not reserve quota for directory expansion when renaming children into a directory. This means that we don't reject the expansion with EDQUOT when we're at or near a hard limit, which means that unprivileged userspace can use rename() to exceed quota.
Rename operations don't always expand the target directory, and we allow a rename to proceed with no space reservation if we don't need to add a block to the target directory to handle the addition. Moreover, the unlink operation on the source directory generally does not expand the directory (you'd have to free a block and then cause a btree split) and it's probably of little consequence to leave the corner case that renaming a file out of a directory can increase its size.
As with link and unlink, there is a further bug in that we do not trigger the blockgc workers to try to clear space when we're out of quota.
Because rename is its own special tricky animal, we'll patch xfs_rename directly to reserve quota to the rename transaction. We'll leave cleaning up the rest of xfs_rename for the metadata directory tree patchset.
Signed-off-by: Darrick J. Wong djwong@kernel.org Reviewed-by: Dave Chinner dchinner@redhat.com Signed-off-by: Leah Rumancik leah.rumancik@gmail.com Acked-by: Darrick J. Wong djwong@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/xfs/xfs_inode.c | 33 ++++++++++++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-)
--- a/fs/xfs/xfs_inode.c +++ b/fs/xfs/xfs_inode.c @@ -3103,7 +3103,8 @@ xfs_rename( bool new_parent = (src_dp != target_dp); bool src_is_directory = S_ISDIR(VFS_I(src_ip)->i_mode); int spaceres; - int error; + bool retried = false; + int error, nospace_error = 0;
trace_xfs_rename(src_dp, target_dp, src_name, target_name);
@@ -3127,9 +3128,12 @@ xfs_rename( xfs_sort_for_rename(src_dp, target_dp, src_ip, target_ip, wip, inodes, &num_inodes);
+retry: + nospace_error = 0; spaceres = XFS_RENAME_SPACE_RES(mp, target_name->len); error = xfs_trans_alloc(mp, &M_RES(mp)->tr_rename, spaceres, 0, 0, &tp); if (error == -ENOSPC) { + nospace_error = error; spaceres = 0; error = xfs_trans_alloc(mp, &M_RES(mp)->tr_rename, 0, 0, 0, &tp); @@ -3184,6 +3188,31 @@ xfs_rename( spaceres);
/* + * Try to reserve quota to handle an expansion of the target directory. + * We'll allow the rename to continue in reservationless mode if we hit + * a space usage constraint. If we trigger reservationless mode, save + * the errno if there isn't any free space in the target directory. + */ + if (spaceres != 0) { + error = xfs_trans_reserve_quota_nblks(tp, target_dp, spaceres, + 0, false); + if (error == -EDQUOT || error == -ENOSPC) { + if (!retried) { + xfs_trans_cancel(tp); + xfs_blockgc_free_quota(target_dp, 0); + retried = true; + goto retry; + } + + nospace_error = error; + spaceres = 0; + error = 0; + } + if (error) + goto out_trans_cancel; + } + + /* * Check for expected errors before we dirty the transaction * so we can return an error without a transaction abort. * @@ -3429,6 +3458,8 @@ out_trans_cancel: out_release_wip: if (wip) xfs_irele(wip); + if (error == -ENOSPC && nospace_error) + error = nospace_error; return error; }